Traction device



L. R. BERGREN TRACTION DEVICE Jan. 9, 1945.

, 1945 2 Sheetg-Sheet 1 Filed July 21 Jan. 9, 1945.

L. R. BERGREN TRACTION DEVICE Filed July 21, 1945 2 Sheets-Sheet 2 1Patented Jan. 9, 1945 PATENT OFFlCE TRACTION DEVICE Lloyd RQBergren,Fairfield, Iowa, assignor to The YLQuden Machinery Company, Eairfield,Iowa,

a corporation 'of Iowa Application July 21, 1943, :Serial N0. 495,645

' 12 Claims. (ICL1O5-FI5A3) This invention relates to overhead carriers,

and particularly to a new drive for such' carriers.

fOverhead carrier devices ordinarily involve a carrier frame withsupporting wheels movable on the upper surface of the flanges of spacedv overhead rails. To propel such carriers, drive wheels are fixed onadrive shaft mounted on the carrier frame in :fixed relation belowthefsupporting wheels. .Heretofore these drive wheels or so-calledairless rubber :tires :for engagement/with the lower surface :of thecarrier rail to drive the carrier when the driveshaft is. ro-

tated. Such driving devices have I given satisfac- :toryservice over along, period oftime. However, theyhave been subject tocertain-disadvantages. The problem of maintaining pressure withinpneumatic :tiresha's been somewhat difficult, due to the high positionof the wheels; and

the internal friction of the .rubber tires, particularly the f'airlessztiresl'has been appreciable,

. ;due to the compression necessary'to obtain the desired traction.Also, when 'power was applied wheels :or v difference in strength ofother rubber wheels, one side of the carrier would start be--fore-the-other and there would result a skewing action which tended-t0strain the carrier frame and to create excessive loadson-tthe carrierrails.

However, because of the simplicity and thegeneral highly satisfactoryperformance of rubber 'wheel drive overhead conveyors, they have 'goneinto very-extensive use. I

It is -an-object of the present invention to provide an improveddrivefor overhead conveyors.

' 'It is another'object tdprovideatraction wheel which may be used'toreplace rubber tired-wheels in existing overhead conveyor. drives.

"It is a further object'of the-invention to provide a new overhead"conveyor driving device which does not requirearesilientrubberwheel andin "which "there isattained decreased fric- .tion losses and a morepositive driving action than in hitherto known driving 'devices.

' It is an additional object .to provide an im- 59 proved overheadcarri'erqcap'able of smoother,

more satisfactory operation. p

Other objects and" dvanta'ges will be inpart explained hereinafter andimpart illustrated, in

the accompanyingdrawinjsS/inwhichaccording *to the :present invention.

driving ring have been equippedwith pneumatic rubber tires 9 Figure lisa plan view of acarrier of anoverhead conveyor involving the presentinvention.

Fig. 2 is an end elevationof an overhead carrier showing -a carrier railwith .the vsupporting wheels and driving wheels of the carrierinoperative relationship on said carrier 'rail.

Fig. 3 is a sectional elevation of a driving wheel Fig. 4 .is a sideelevation of a which may-be employed in the driving wheel of the presentinvention;-

*Theqcarrier shown einEigs. land 2 is constructed for operation in anoverhead conveyor system having spaced parallel carrier rail mem- -berstllsuspended fromra ceiling or other sup- :port :(not shown) andprovided at their lower vedges. with substantially horizontal flanges12. The carrier :14 comprises a rigidly braced frame extending :betweenspaced carrier rails l0, and supporting trucks "E8 in which .are mounted:pairs of opposed flanged supporting wheels 20 resting onztheuppersurfaces 12:! of thelfianges 1. of the {carrier rails. ,A power:operated drive vshafts22 supported .by thelcarrier \frame J5 extendsbetween :carrier railsulll in substantially :fixed' relationship :below.the, supporting wheels v2,0.

H'Jhe 'newwdrive wheels 214 of the present ,invention are mounted on the:drive shaft 22 and enga e the lower surfaces 25 of the I carrier rail1.0 and operate to-drive the c rr er .4 w en he drive shaft 22 isrotated, vAs shown -pparticularly in Fig. these ,new driving Wheels 24.involve, resiliently pressed-together disk-like drive :members 28grand-3. cooperating to vform outawardly diver in circular grooves 32,andrine members 34 .with portions of their edge surfaces .35iniengagement with the diverging drive surfaces 38 and All-otthe-drivemembers 28 and 30,

- =and with :thBiIiPQTiPhQI'i-GS 42 pressed into fric- .tionalengagement withthelower surfaces 26 of the ,carrierlrails H) :by thepressure of the drive surfaces.

As :shown more clearly in Fig. ,2, the carrier w rails l0 are suspendedfrom aceiling'or other. surfacebymeans of adjustable stringer bolts 44,secured to brackets 46 on-the upper portions of the I-beams. Pairs :ofopposed .fianged wheels 72B resting on the zuppervsurfaces 2| of thelower :flangesofthe I-beams are rotatably mounted on stublshafts4.8,fi'xed at the endsof the arms of jy kesififl which are.,mountedatthe pp it ends- 52 of each vcarriage-supporting truck I8.

As ,showninlFigs. l.andi2 thetcar'rierrframe I6 comprisesa pairofspacedparallel end members dob-:54 parallel to leacn fcarrier rail l0,transverse opposed Wheels are rockably connected to the carrier frame 18and equalize the load on the wheels 20, notwithstanding irregularitiesor unevenness of the carrier rails H].

A gear reduction motor unit 64 mounted on the carrier frame It isconnected to rotate the drive shaft 22 which extends parallel to thetransverse members 56 between the carrier rails l0. Power may besupplied to the motor unit 64 b any suitable means such as power wiresor bars (not shown) parallel to the supporting rails Ill and the motormay be controlled by any suitable controller. The drive shaft 22 ismounted in bearings 88 in fixed relation to the carrier frame If) adetermined distance beneath the flanged supporting wheels 20. Drivingwheels 24 are mounted on the drive shaft 22 in position for engagementwith the lower surgagement therewith to drive the carrier 14 when thedrive shaft 22 is rotated by operation of the motor.

As shown particularly in Figs. 3 and 4, each drive wheel 24 comprises afirst disk-like driving member 28 integral with a sleeve portion 68having a bore Hi for snug engagement with the drive shaft 22. Thisdriving member 28 is keyed to the shaft 22 for rotation therewith by akey 12 cooperating with a slot ".14 on the shaft 22 and a slot 76 on theinterior of the sleeve 68. The exterior of the sleeve portion 58 is asmooth cylindrical surface I8. A second disk-like driving member 30having a sleeve portion 80 with a. bore 82 portion 68 of the firstdisk-like member 28. Stud bolts 84 in threaded engagement with the firstdisk-like member 28 extend .parallel to the drive shaft 22 throughopenings 88 in a flange 88 at the inner end of the sleeve 80 of thesecond disklike member 3!]. Compression springs 90 are disposed on theportions of the bolts 84 extending through the openings 85 and areheldin compressed position between the flange 88 and nuts 92 secured to theends of the stud bolts 84, so that the disk-like members 28 and 30 areresiliently urged together. Also, the stud bolts 84 engage the flange 88of the second driving member 33 to supply power thereto and cause it torotate with the first driving member 28.-

The surface portions 38 and 40 of the disklike members 28 and 38,respectively, extend outwardly away from each other, forming a divergingcircular groove 32. In the construction shown in Figs. 3 and 4 theoutwardly extending surfaces 38 and 40 are frusto-conical, the conicalsurfaces being at an angle of approximately 60 to each other. The angleof 60 has been found highly practical but is not critical, since theangle may be appreciably greater or appreciabl less, depending on theresults desired. For example, if it is desired to increase the pressureof the ring 34 on the lower surface 26 of the rail I8 relative to the.pressure of suitable dimensions is slidably 7 -mounted on the outersurface 18 of the sleeve faces 26 of the carrier rails IQ for frictionalenof the ring on the drive surfaces 38 and 48, the angle could beincreased and vice versa.

The driving ring member 34 is disposed between the oplposed frustoconical surfaces 38 and 40 of the disk-like driving members 28 and 30.As shown in the drawing, the ring 34 involves two surfaces 36 for drivenengagement with the frusto-conical surfaces 38 and 48 of the disk-likemembers 28 and 38 disposed at an angle equal to the angle between thefrustoconical surfaces of the disk-like driving members, i. e., at anangle of 60 to each other, and a peripheral surface 42 for drivingengagement with the lower surface 26 of the carrier ral at an angle of60 to each of the other surfaces.

The pressure, of the springs 90 resiliently urging the disk-like members23 and 30 together, creates a component of force on the ring 34 stronglypressing it into firm frictional engagement with the carrier rail ID.The lower portion of the ring 34 is out of contact with thefrusto-conical surfaces 38 and 40 of the disklike members 28 and 30, sothat the ring 34 can be forced up or down by the action of thefrustoconical members 28 and 30 or of the carrier rail i0, respectively,to accommodate difierences or irregularities in the carrier rail.

As shown particularly in Figs. 3 and 4, a preferred form of the ringmember 34 comprises a plurality of laminae 94 of fibrous material suchas paper fiber disposed at right angles to the axis of the ring 34. Thelaminae 94 of fibrous material are impregnated with a resinous materialsuch as tar, which strengthens the fibrous material and binds ittogether into an integral mass. In the construction of this ring 34,dowel pins 96, preferably of wood, are inserted in holes 93 drilled inthe laminae 94 parallel to the axis of the ring member 34 at equallyspaced points around the periphery of the ring. When the ring member 34has been formed and impregnated, a series of additional holes 99 areformed around the periphery of the ring, metal rings 100 are placed onthe face of the ring coaxial with the ring in a position to cover theholes 98, and a series of rivet members I02 are inserted through themetal rings I and holes 88 in the ring member 34 and riveted in place.

In the operation of the carrier 14 the rings 34 are, strongly pressedinto firm frictional engagement with the carrier rail It] by the springsacting through the disk-like driving members 28 and 30 and the conicalsurfaces 38 and 45. Also, the spring pressure effects a firm frictionalengagement between the conical surfaces 38 and 40 of the members 28 and38 and the edge surfaces 36 of the ring member. When the drive shaft 22is rotated by operation of the gear reduction motor unit 64 the drivingmembers 28 and 38 act onthe rings 34 which in turn act on the carrierrails 18 to drive the carrier. The rings 34 are notappreciablydistortab-le under the action of the driving members so thata firm uniform positive driving relation is secured between the motorunit 54 and the rails I0, and thecarrier will be started smoothlywithout skewing action. Also, since the ring is substantiallyundistorted, there will be substantially no internal friction toovercome, and consequently there will be less power loss.

' for resiliently pressing together the diverging surfaces of thedriving disc. Also the "driving mechanism can be employed where only aheatfrubber' cannot h e used. Also, the driving mechanism operates'witha drive Shaft in fixed relation to the carrierrail so that it may beused to replace rubber drive wheels now in use.

The driving ring maybe easily removed without the use of special toolswhen it needs to be replaced, and the driving pressure against the un- Qder sideofthe carrier rail can be controlled by adjustment ofthe nutsretaining the springs, or

by thesubstitution' of different sized springs.

" .While thev construction hereinabove described has been found highlysatisfactory in use, it will be appreciated that modificationsor 1variations may be made in the structure specificallyshown 'without'departing from the spirit of the inven-' ti'onq @Thus, it is notnecessary that the, ring be formedof laminated fibrous material, sinceother single carrier rail and/orsingle driving wheel is provided,Accordingly; it will be apparent that the invention is not restricted tothe specific details shown and described, and it is to be understoodthat the claimsare'to be construed as covguage may be held'tofall withinthe accompanyin'g claims.

"ering allstructures which as a matter of lan- 1. A traction,deviceco-mprising coaxial, out- I wardly diverging drive surfacescooperating to form a circular groove, an endless friction memberdisposed with portions of its inner surface in engagement with saiddiverging drive surfaces,

and means acting through said drive surfaces urging said'endless member,portions away from the, axis of saidvdrivesurf aceslfor tractionengagement with another surface, said :endle'ss memberybeing ofsuchlength that when exerting tangential force it will be intangentially driven frictional rolling engagement with said drivesurfaces.

2. A traction device comprising coaxial, outwardly diverging drivesurfaces cooperating to form a circular groove, a ring member withportions of its inner surface in-engagement with said diverging drivesurfaces, and resilient means acting through said drive surfaces urgingsaid ring member portions away from the axis ofsaid drive surfaces forengagement with a surface, said ring member being of such length thatwhen exerting tangential force it will be in tangentially drivenfrictional rolling engagement with said drive surfaces. Y

3. A traction device comprising coaxialopposed conical members forming acircular, substantially V-shaped groove between them, a ring member withportions of its inner surface in engagement with said conical members,and resilient means acting through said conical members urging said ringmember portions away from the axis of said conical members forengagement with a fixed to force said endless member portions away fromit will be in tangentially drivenfrictional rolling.

flow the supporting wheel, outwardly diverging drive surfaceson saiddriving wheels cooperating to form a circulargroove between them, anendless friction member with portions of its inner surface in engagementwith said diverging drive,

surfaces, and resilient means acting through the drivingwheels and saiddiverging'drivesurfaces the axis of said driving wheels and force saidendless member resiliently against the lower surface of said rail, saidendless member being of such length that when exerting tangential forceengagement with said drive surfaces.

5. In an overhead conveyor system, a rail, a supporting wheel adaptedfor travel on said rail, a

' carrier supported by said supportingwheel, a

drive shaft movable with said carrier and supported a substantiallyconstant distance below said rail, means to rotate said shaft, a drivewheel mounted on said shaft for rotation therewith, and an endlessfriction member resiliently pressed between said wheel and said rail,said friction member being formed of relatively stiff material which isnot,substantially distorted'under load, succeeding portions of saidfrictionmember-being forced toward the axis of said drive wheel by saidrail as they approach the place of maximum pressura "6. In an overheadconveyor system, a rail, a supporting wheel adapted for travel on saidrail, acarrier supported by'said supporting wheel, a drive shaft movablewith said carrier and supported a substantially constant distancebelowsaid rail, means-to rotate s'aidshaft, a V-groove'd wheel mounted onsaid shaft for rotation there- ,with and having two coned sides movablerelative to each other axially of the shaft, means resiliently urgingsaid sides towards each other to increase the effectivev diameter ofsaid wheel, and an endless friction member pressed between said sidesand said rail, succeeding portions of said friction member being forcedtoward the axis of said wheel by said-railas -they approach-the place ofmaximumpressure.

'7. An overhead conveyor comprising spaced carrying rails, supportingwheels mounted for movement on each of said carrier rails, a carriersupported by said supporting wheels on said spaced carrier rails, anddriving means compris ing a drive shaft'movable with said carrier andsupported a substantially constant distance below said carrier rails,means to rotate said shaft, drive wheels mounted on said shaft forrotation therewith' and positioned substantially below each of saidspaced carrier rails, and endless friction members for each of saidwheels, said friction- -members being resiliently pressed between saidwheels and said rails, and being-formed of stiff material which is notsubstantially distorted under load, succeeding portions of said frictionmembers being forced toward the axis of said drive wheels bysaid rail asthey approach the place of surface, said ring member being ofsuch lengthhead conveyor comprising a supporting wheel for engagement with anoverhead rail, and a trac- 'tion device comprising coaxial drivingwheels with their axis at a substantially fixed distance bemaximumpressure. 8. An overhead carrier comprising spaced overhead carryingrails, supporting wheelsmounted for movement on each of said overheadcarrier rails, a carrier supported by said supporting wheels on saidspaced carrier rails, and driving means comprising a drive shaft infixed spaced relation below saidsupporting wheels, extending betweensaid spaced carrier rails, means torotate said shaft, V-grooved wheelsmounted on said shaft for rotation therewith in positions below each ofsaid carrier rails, each of said wheels having two coned sides movablerelative to each other axially of the shaft, means resiliently urgingsaid sides towards each other to increase the effective diameter of saidwheel, and an endless friction member resiliently urged outward by thepressure of said sides into frictional engagement with said rail,succeeding portions of said friction member being forced toward the axisof said drive wheel by said rail as they approach the place of maximumpressure.

9. An overhead conveyor comprising spaced overhead carrier rails,supporting wheels mounted for movement on each of said overhead carrierrails, a carrier supported by said supporting wheels on said spacedcarrier rails, and driving means comprising a drive shaft in fixedspaced relation below said supporting wheels, extending between saidspaced carrier rails, and having a traction device mounted at each endof the shaft for driving engagement with the lower surfaces of saidspaced carrier rails,-each of said traction devices comprising coaxialdriving wheels mounted on said drive shaft, outwardly diverging drivesurfaces on said wheels cooperating to form a circular groove betweenthem, means resiliently urging said driving wheels together, and a ringmember with a portion of its inner surface in engagement with saiddiverging drive surfaces, the

cross section of said ring member being such that the outer periphery ofthe ring member is adapted to be forced into frictional engagement withthe lower surface of an overhead carrier rail by the resilient meansacting through the driving wheels and the diverging drive surfaces onthe inner surface of the ring member, succeeding portions of said ringmember being forced toward the axis of said wheels by said rail as theyapproach the place of maximum pressure.

10. In a traction device comprising a drive shaft, and a drive ring fordriving engagement with a surface, a drive surface fixed to a sleevemounted on said shaft for rotation therewith, a second drive surfacefixed to a sleeve coaxial with 'the first mentioned sleeve, said drivesurfaces diverging outwardly away from each other to form a circulargroove, and means resiliently urging said drive surfaces towards eachother, to force said drive ring against said surface, succeedingportions of said ring being forced toward the axis of said drivesurfaces by said rail as they approach the place of maximum pressure.

11. In a traction device comprising a drive shaft, a drive ring fordriving engagement with a surface, a drive member comprising a drivesurface fixed to a sleeve mounted on said shaft for rotation therewith,a second drive member comprising a drive surface fixed to a sleeveslidably mounted onthe exterior of said first mentioned sleeve, saiddrive surfaces diverging outwardly away from each other to form acircular groove, and means acting through said drive members resilientlyurging said drive surfaces towards each other, to force said drive ringagainst said surface, succeeding portions of said ringbeing forcedtoward the axis of said drive surfaces by said rail as they approach theplace of maximum pressure.

12. A traction device comprising a drive shaft, a drive ring for drivingengagement with a surface, a drive member comprising a drive surfacefixed to a sleeve mounted on said shaft for rotation therewith, a seconddrive member comprising a drive surface fixed to a sleeve slidablymounted on the exterior of said first mentioned sleeve, said drivesurfaces diverging outwardly away from each other to form a circulargroove, a flange at the end of the second-mentioned of said sleevesnearest the first-mentioned of said drive surfaces, spaced holes in saidflange, bolts with one end rigidly fixed in the first-mentioned of saiddrive members, extending through the holes in said flange, and resilientmeans acting between the flange and the portions of said bolts extendingthrough said holes urging said drive surfaces together, to force saiddrive ring against said surface, succeeding portions of said ring beingforced toward the axis of said drive surfaces by said rail as theyapproach the place of maximum pressure.

LLOYD R. BERGREN.

